From 7b3671cd14cc37fca3f47a017a88dd52cf1c8358 Mon Sep 17 00:00:00 2001
From: "Enrico Weigelt, metux IT consult" <info@metux.net>
Date: Wed, 4 Sep 2024 18:42:15 +0200
Subject: [PATCH] dix: lookup function for WindowPtr by XID

This new lookup function retrieves a pointer to WindowRec structure by
associated XID. Unlike dixLookupWindow(), this one works globally, instead
of just on one specific client, and it doesn't do any XACE calls.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
 dix/dix_priv.h | 11 +++++++++++
 dix/lookup.c   | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/dix/dix_priv.h b/dix/dix_priv.h
index c8abe051fc..c7770bbde4 100644
--- a/dix/dix_priv.h
+++ b/dix/dix_priv.h
@@ -807,4 +807,15 @@ static inline void SwapLongs(CARD32 *list, unsigned long count) {
 #define SwapRestL(stuff) \
     SwapLongs((CARD32 *)(stuff + 1), (client->req_len - (sizeof(*stuff) >> 2)))
 
+/*
+ * @brief lookup window by XID
+ *
+ * This globally looks for Window with given XID (all screens, all clients)
+ * and returns a pointer to it. If not found, returns NULL.
+ *
+ * Unlike ::dixLookupWindow() it doesn't scan only one given client, nor does
+ * it do any XACE calls.
+ */
+WindowPtr dixLookupWindowByXID(Window window);
+
 #endif /* _XSERVER_DIX_PRIV_H */
diff --git a/dix/lookup.c b/dix/lookup.c
index 406f702645..dee11b457a 100644
--- a/dix/lookup.c
+++ b/dix/lookup.c
@@ -39,3 +39,35 @@ ClientPtr dixClientForOtherClients(OtherClientsPtr pOtherClients) {
 
     return dixClientForXID(pOtherClients->resource);
 }
+
+struct window_xid_match {
+    WindowPtr pWin;
+    Window id;
+};
+
+static int dix_match_window_xid(WindowPtr pWin, void *ptr)
+{
+    struct window_xid_match *walk = (struct window_xid_match*) ptr;
+
+    if (walk->id == pWin->drawable.id) {
+        walk->pWin = pWin;
+        return WT_STOPWALKING;
+    }
+    else
+        return WT_WALKCHILDREN;
+}
+
+WindowPtr dixLookupWindowByXID(Window window)
+{
+    struct window_xid_match walk = {
+        .id = window,
+    };
+
+    for (int i = 0; i < screenInfo.numScreens; i++) {
+        WalkTree(screenInfo.screens[i], dix_match_window_xid, &walk);
+        if (walk.pWin)
+            break;
+    }
+
+    return walk.pWin;
+}